The present invention relates to a vacuum switching tube, particularly one having axial magnetic field electrodes.
A vacuum switching tube is disclosed in "IEEE Transactions on Power Apparatus and Systems", 1980, pages 2079 to 2085, which comprises a vacuum-tight housing and magnetic field electrodes disposed in the housing movable relative to each other. Each electrode is supported by a conductor rod and comprises a coil or field winding which includes a ring and two spokes extending diametrically through the ring at right angles to each other. Two raised parts on one of the spokes are provided adjacent the hub as current transfer points. A main contact is disposed entirely covering the ring and spokes. Operation of such magnetic field electrodes is based on the generation of an axial magnetic field which counteracts the contraction of partial arcs to form a spatially concentrated arc discharge. In contrast to a diffused discharge occurring at low currents, the concentrated arc is accompanied by a large anode spot and a relatively high operating voltage as well as by high power consumption, which leads to melting at the main contacts and heavy evaporation of material.